Britons are getting bigger and it's a crisis on the same level as climate change, says the government. Within 15 years most of us will be overweight, with our life expectancy cut by 13 years. Scary stuff, but do all the facts about this "ticking time bomb" really add up?

It's headline grabbing-stuff. The obesity epidemic in Britain is now a crisis on a scale with climate change, says Health Secretary Alan Johnson.

It will lead to the first cut in life expectancy in the UK for 200 years. "Children are likely to die before their parents," says Dr Colin Waine, chair of the National Obesity Forum.

The Investigation is broadcast on Thursday, 22 November at 2000 GMT on BBC Radio 4

There's just one problem with this claim - official forecasts show it's not true. The government-commissioned Foresight report released last month [see internet links, right] looked at the future trends of obesity and found an increase will have surprisingly little impact on life expectancy. In fact it predicted Britons will live significantly longer. So what is the truth about the obesity epidemic?

The UK is certainly getting heavier. The weight of adults and children is on the rise, with the annual health survey - conducted by the National Centre for Social Research - showing a clear upwards trend.

"If you look at men they have become around half a stone heavier on average than they were in 1993," says Heather Wardle, a senior researcher at the centre.

This weight gain matters because it means more and more of us are becoming overweight and unhealthy, argue anti-obesity campaigners. Putting any weight on after your 21st birthday is even a risk, according to last month's World Cancer report.

'Arbitrary' figures

No one denies extreme obesity is bad for you, but some are now standing up to defend the overweight. Professor John Evans, from the School of Sport and Exercise Sciences at Loughborough University, doesn't believe the predictions.

"There is very little evidence to say that being overweight is a signifier of a person or a population's health," he says.

This may sound like heresy but there is good science to back it up. Only this month a study, led by Katherine Flegal of the USA Centre for Disease Control, reported that those who are overweight had no higher risk dying of cancer or heart disease and overall lived longer than those of "normal" weight. You might be surprised at her finding but she was not.

READ THE FINDINGS

The increase in obesity will have surprisingly little
impact on period life expectancy of the
population

"There is actually a large amount of evidence that suggests that the overweight live the longest," she says.

It's certainly not the public health message you normally hear.

For instance, a recent study by Cancer Research UK reported that 6,000 women a year get cancer because of obesity.

But look closer at the detail of the report and you find an unreported story. This research also found the overweight are no more likely to die of cancer than the slim.

"Overall there is no evidence of a strong increase in risk in being overweight, but there is evidence of a significant increase for people who are obese," says Doctor Gillian Reeves, who led the study.

'Built on sand'

One of the most alarming statistics about obesity is that a third of children are now overweight. We are told that weight is now even a problem among the youngest school children.

An estimated 25% of 5-year-olds are now overweight, according to the government's Health Survey for England. That might be the statistic, but some are still sceptical.

"Many of the teachers we talk to can't recognise the epidemic of obesity that is always reported," says Mr Evans.

When you visit schools it's certainly hard to find these large numbers of overweight kids. Doctor Linda Voss is the co-ordinator of the Early Bird Study, which is looking at the links between childhood obesity and diabetes. Put on the spot in a school even her expert eye failed to spot these numbers of fat kids.

Like many experts, she thinks it's our view of normal that has changed.

"I think I failed to spot the overweight kids because we are so used to seeing overweight kids these days," she says.

But another reason we can't see them could be because the figures are misleading. The figures the government use are based on a 1990 benchmark. It put the weight and height measurements from different surveys on a graph and decided that the top 15% of kids would be called overweight and the top 5% obese. As our children have got heavier, more and more have passed these benchmarks.

If you think the benchmarks seem rather arbitrary, the first to agree with you is the man who came up with them.

Scare the public

"I've taken a graph and drawn a line on it," says Tim Cole, professor of medical statistics at the Institute of Child Health.

"I'm not saying they are healthy and they are not. The idea that these numbers are cast in stone is absolute nonsense. It is all built on sand."

But the UK's way of calculating obese and overweight children isn't the only one. If we adopted the international standard we would roughly cut our figures for fat children in half.

Experts like Professor Cole say that whatever figures you use, the underlying trend is going up. But critics say big scary statistics are a good way to unsettle the public and justify government intervention.

It's predicted obesity will cut life expectancy by 13 years

At last month's annual conference of the National Obesity Forum there was a vote of no confidence in the government policy on dealing with Britain's weight problem.

Forum board member Tam Fry was one of those who spoke out against the government. He has worked for a charity for years to publicise the risks of obesity. Yet he is obese himself.

"Technically I am obese," he says. "But if you look at my size, my age, my height and my body type, I am not outstandingly obese."

He is clear that he isn't blaming the government for his obesity, it was just that his obesity isn't a problem.

The obesity statistics are full of people, who like Tam, are fine at their weight. It's the small minority of very obese that are the problem, not the two-thirds of us the government defines as overweight.

When rugby players and weight lifters are branded obese simply for being very tall or very muscular, it suggests that the way we measure obesity is no longer fit for purpose. It may serve as a useful stick for the government to beat certain "wicked" or "gluttonous" members of the public with but, when you are told you have a "sky high" BMI reading by a medical professional who is fatter than you, you begin to wonder if the system is still working...Dave, Cheltenham, UK

This adds even more to my belief that people should stop obsessing about their weight and numbers and just look at what they are eating and how much exercise they are doing. There are many slim people who do all sorts of unhealthy things to keep their weight down (smoking, slimming pills, diets); how can they possibly be healthier one the sole basis of weighing less? Being physically healthy is about making a life-long commitment to eating a balanced diet and getting enough exercise; if you know you're doing that, you can throw the scales out!Birgit Holland, Newmarket, UK

At last- an honest story- fatism is rife, and led by government's interference in this nanny state. We should be helped to tackle our wieght problems, not berated for being unable to do so ourselves, and not looking the "beautiful norm".Pam, Cardiff

We used to believe scientists and what they told us. We used to believe official reports. Now it turns out that, more often than not, they are telling us nonsense. We just want the truth.
Sensationalist scaremongering used to be confined to the tabloids. Now it¿s done by every quango and official body in an effort to justify their existence.Tim H, UK

Whether or not obesity affects life expectancy, it is still a big problem. Obesity should not be played down. If you're fat, you're fat no matter how you measure obesity. Obese people should think about the starving people in the third world before they put a cake in their mouth.Anon, London

"Big scary statistics are a good way to unsettle the public and justify government intervention." They don't just create fear, they create division. Read the comments made about people who claimed they were too overweight to work last week and you will see a clear hatred of overweight and obese people in the minds of many of the public. To give this government backing by statistics is dangerous.
Most overweight and obese people probably don't want to be like that, but creating fear doesn't help. Stress is often a major factor in the problem in the first place.Paul, Cusco, Peru

Saying obesity is on the same level as climate change is just ludicrous, and I expect it was said to scare people (a few years ago they probably would have said it's on the same level as terrorism).
I don't think the problem is that children are fat, it's that they eat unhealthily (fast food and such) which effects a lot of children, not just the ones who become fat as a result.William Clinch, Wells, Somerset

It would help if the government would recommend using body fat measurements rather than the BMI scale when assessing obesity. The BMI has been proved over and over again to be inaccurate and yet they keep on peddling out like it's the holy grail of health measurements. I do a lot of sport, therefore I have a lot of muscle and even though I have a healthy body fat measurement and am physically fit, I am denied access to medicines on the grounds that the BMI says I am overweight. Hugely unfair and detrimental to my health.
Genie, Bristol

I think this is a typical 'Nanny State' distraction. Spin the statistics, make personal attacks on individual groups in the population and the population is distracted from the the mess being made of the economy, education, policing, immigration, terrorism, war etc. i.e anything that affects everybody.Tony Borrett, Daventry

That's the problem with scientists in a nutshell! You can always find someone to promote any idea if you look hard enough, and of course the ones the media publicise most are the ones who come up with the most outlandish statements - 'cos that's NEWS!Phil Met, Eastbourne

Fatism! Eat less rubbish and get some exercise, it's not rocket science.Chris, London